1. Field of Invention
The invention relates to a method and an apparatus for dislodging the cake of a chamber filter press. In a chamber filter press, two respective filter cloths which enclose a filter plate located therebetween, are fastened on said plate by means of a connecting part and on the underside thereof by means of lashings. The filter cloths are free laterally with respect to the filter plates and, when the chamber filter press is open, they can be stretched apart from one another. The upper ends of the filter cloths are provided with eyelets. In this arrangement, two adjacent filter cloths are fastened together on a series of springs which, for their part, are suspended on a mobile crossmember. The latter is supported on the chamber filter press such that it can be displaced parallel to the charging channel and can move vertically. It is preferably supported on sliding guides or rails which, for their part, may be supported on the chamber filter press such that they can move in the vertical direction. Springs assigned to two adjacent filter cloths and to a common cross member preferably have different degrees of hardness. A photocell and a light source may be arranged beneath the filter plates. When the chamber filter press is open, the cross member is lowered and raised up, preferably shaken, by a displacement intended to produce shear forces. In addition, said crossmember may be lowered and raised up in order alternately to relax the filter cloths and tighten them.
Chamber filter presses have been used for a long time in various industries for separating sludge into solid and liquid portions. Depending on the type of sludge, the sludge cake is dislodged automatically, with manual assistance or with the aid of apparatuses for dislodging the cake.
2. Description of the Prior Art
Nowadays, chamber filter presses are also used in the waste industry and in the basic-material industry. Chamber filter presses are used in the gravel industry, for example, in order to dewater the partly clay-containing sludges produced when washing gravel. As a result, process water is re-used to a large extent and a largely problem-free disposal of the solids, occurring in the form of sludge cakes, is achieved. The sludge cake may, however, be very sticky, this, as a rule, preventing it from being dislodged automatically. Since the matter in hand concerns waste disposal, a supervisor, who would assist in dislodging the cake, if appropriate by manual intervention, has to be dispensed with on the grounds of cost.
A reliable and automatic apparatus for dislodging the cake of the chamber filter press is thus a prerequisite in order to be able to operate a chamber filter press around the clock. Even if only a single cake or cake portion remained attached on the filter cloth, there could be a danger of the press, in the next operating cycle, not being tightly sealed and of the sludge therefore escaping from the leakage point when the press is re-charged, and this would generally have grave consequences.